The only other multiple winner was the hip-hop duo UGK, consisting of Bernard "Bun B" Freeman and the recently deceased Chad "Pimp C" Butler. In all 15 awards were handed out during a three-hour show mixing the heroes of contemporary hip-hop and old-school R&B.
Keys, flying high with a successful worldwide tour, a chart-topping album and an upcoming film, shared the stage with three leading female ensemble acts from the 1990s -- TLC, En Vogue and Sisters with Voices -- for a medley of R&B music.
She went on to win the prize for best female R&B artist, and offered a heartfelt endorsement to Obama, who would be the first African-American elected to the nation's highest office.
"Together we can do anything -- Obama, y'all!" she enthused.
Teen sensation Chris Brown, who topped the U.S. singles chart last year with "Kiss Kiss," was named best male R&B performer.
AL GREEN IS SORRY
The evening's most spine-tingling moment came when veteran soul crooner Al Green, recipient of a lifetime achievement award, got the audience in the Shrine Auditorium on its feet singing, and dancing, along with his classic 1970s hit "Let's Stay Together."
Backstage a short time later, Green apologized.
"I'm sorry I didn't sing as well as I should because I got scared. I was nervous," he said. Green, 62, earlier this month hit the top 10 of the U.S. pop chart with his first album in three years, "Lay It Down."
West, whose third album, "Graduation," was one of 2007's top-selling releases and spawned three Grammys, was named best male hip-hop artist and shared a second BET prize with R&B singer T-Pain for their collaboration on the hit single "Good Life."
"This man, T-Pain, is a genius," West declared onstage of his co-winner, resplendent in metallic silver-and-black patterned top hat and tails and oversized shades. "I'm one of the kings in this game right now, so my opinion counts."
T-Pain, a southern soul singer with a best-selling ringtone adapted from his hit single "Buy U a Drank," was visibly humbled and euphoric.
"I appreciate it everybody," he said. "Three years ago, I couldn't even get a ticket to get up in here." T-Pain entered the show with the most nominations, five in all.
UGK, whose album "Underground Kingz" topped the charts last summer, won the BET prize as best group and shared the award for best video with the hip-hop duo Outkast for their work together on "International Player's Anthem (I Choose You)."
It was a bittersweet triumph for UGK, coming just six months after Butler, 33, was found dead in a Los Angeles hotel. Two days later UGK received a Grammy nomination for the song "International Player's Anthem." Butler had previously served nearly four years in prison for aggravated assault.
Freeman, aka Bun B, now pursuing a solo career, said he hoped "to keep Pimp C's legacy alive" with a new UGK album due out this fall.
The prize for best female hip-hop performer went to Missy Elliott, who has not had an album out since 2005 but has a new CD set for release in August.
The Dream was named best new artist, and the viewers' choice award, determined by an online vote of fans, went to Lil Wayne and his single "Lollipop," featuring Static.
The best and actress awards went to Oscar winners Denzel Washington and Halle Berry, neither of whom attended.
The eighth annual BET Awards was presented by the BET (Black Entertainment Television) Networks cable group, which carried the three-hour show live.